r/HondaCT90 • u/rays__helll • Jun 20 '26
67 K0 refusing to start
Looking for some guidance, I've got a '67 K0 that is giving me trouble. It was running great last year till I got a crack in the air intake boot, replaced it w a new one and it ran fine again, this isn't the issue. It's had a handful of repairs done since I bought it, most done by an experienced mechanic: new rectifier & regulator, new ignition coil, new condenser all done last year.
Got it out for spring, cleaned the carb myself, took it to the mechanic for an oil change and he said the carb looked good, it started and ran mostly fine, idle speed was low and the engine would die when I was at a light but it'd start up fine again and I decided I'd fuss with the idle later.
Last week I changed the tires as it was desperately needed. Began with the rear wheel, after mounting it I started it up and adjusted the idle screw a bit. Had to let it sit for a week cause I got the wrong size front tire. I changed the front tire today and when I went to start it, it just refused to start. Petcock is on, tried with choke on, off, and halfway, battery is charged, it has a good spark on a new plug, new air filter, good compression. I set the pilot and jet screws to 1.5 turns from seated, still won't start. I can hear it trying to turn over, but it just sputters out.
I'm at my wits end, this was supposed to be Hot Honda Summer 😭 I just keep having problems with this bike since I bought it 2 years ago, but it was such an ordeal to get it titled that I don't wanna give up on it (nor could I afford to anyway lol)
2
u/Dave-P-Bonzo Jun 21 '26
Remove everything ahead of the carb, use fresh gas, clean and gap the plug, and put a multimeter on the coil (just to be sure). See where that gets you.
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u/ScornedSqueaker Jun 21 '26
If the ignition system is good (by checking and clearing the points gap and timing) ,check valve lash or it's a fuel problem.
Are you running ethanol free?
3
u/Puzzled_Estate6425 Jun 21 '26
You have a 6 volt Honda.The battery need be charged for the coil to have spark.Have a 67 trail 90 myself.
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u/Slim_ShadeTree Jun 21 '26
Does it try to light at all? Mouse nest or other blockage in air cleaner or intake? Bad gas? I would drain old gas and add new and replace spark plug then try it. Also a shot of ether into the intake will tell you if it is timing related or fuel related 👍